Automotive automatic transmissions typically include a park brake assembly to maintain a vehicle in a “parked” position or state. Park brake assemblies often include a rotatable member (or “park pawl”) that is rotatable about a pivot shaft. A park pawl may be selectively engaged by a park rod when the transmission of the vehicle is shifted into the “park” position. When the park rod engages the park pawl, the park pawl pivots or rotates into a position where it is disposed between a pair of teeth on a park gear, thereby substantially preventing the park gear and corresponding output shaft from further rotating. This constrains the vehicle against movement under gravity when the vehicle is parked on a sloped surface, for example.
When a vehicle is shifted into a position other than the “park” position, a return spring biases the park pawl away from the park gear and out of engagement with the teeth of the park gear. The return spring also serves to ensure the park pawl stays disengaged from the parking gear when the vehicle is not in “park.” This may be accomplished through torsion created in active coils of the return spring by grounding one end of the return spring at a position on the park pawl, and grounding the other end of the return spring at a pin or other grounded surface within the transmission housing. In this way, the active coils of the grounded return spring bias the park pawl away from the park gear during operation of the vehicle while it is not in “park.”